For a river, measurements of hydrologic parameters are helpful to early warning of floods, safety of persons and bridges, etc. The parameters are such as water levels, flow speeds, riverbeds, sand density in the flows, etc. However, currently, other than water levels, other hydrologic parameters are measured manually. For example, in measurement of the height from the riverbed to the surface of a river, conventionally, a weight is tied to a rope and then they sunk into water and then to the riverbed. The length from the river surface to the riverbed can be derived by the height of the bridge to the river surface subtracting the length of the rope. However, the rope is easy to vibrate and thus is not vertical to the river surface. Especially, as great wind blows, due to wind force or water flow, the rope is bent greatly to affect the measurement results.
Practically, in typhoon period, flood flow is strong, under the consideration of personal safety or when the bridge is closed, manual monitor cannot be realized all day long so that it is very possible that no data is monitored when the flow is at a peak value. As a result, the system can not provide an effective assistance.
Although some manual operations are planned to be preformed, the time period is too long to get affect data. Furthermore, at night or heavy rain period, the personal safety and precision of the result are greatly affected. Therefore, there is an eager demand for a novel automatic monitoring system which can provide effect monitor results to replace the conventional manual operations.